IL-2 is a biological response modifier that can improve the body's response to disease. It is hoped that IL-2 treatment can help restore CD4 cell counts and immune function in people whose immune systems have been damaged by HIV. Over the last 10 years, NIAID has sponsored a number of important studies of IL-2 in HIV infected people; many of these trials are ongoing. This study was developed in an effort consolidate these separate, smaller trials into one larger study so that results between the trials can be shared and used to develop future protocols. This study is an umbrella study that will provide long-term administrative support, treatment, and monitoring for ongoing Phase I and II IL-2 trials and their participants. It is primarily intended for patients in the extension phases of any previous NIAID Clinical Center HIV Program (NIAID/CCMD) intramural research protocols in which IL-2 therapy continues to be offered. Blood collection will occur through a patient's participation in this study.